High-intensity interval training won’t keep you from aging

EXERCISE is hard. That should go without saying, but it’s worth acknowledging. It’s difficult enough to instill a new habit without all the things that makeexercise uniquely un-pleasant at first. You generally have to go to a crowded place full of cranky strangers, share equipment in close quarters, and sweat and shower along-side them. But on top of that, oh yeah, it’s hard. A lot of the movements are weird and awkward for newcomers. Maybe you have to stick your butt up in the air, or wiggle around like a wet noodle in overpriced, stretchy clothing. It’s not surprising that so few people stick to a regular workout regimen, because to some degree, if it’s not hard, you’re not doing it right.
But we all hold out hope for a mythical exercise routine that’s short, simple, and will give us all the benefits of a truly difficult workout—plus a great diet—without actually feeling too hard. Enter: high-intensity interval training. HIIT, as it’s commonly known, involves short bursts of strenuous activity interspersed with rest. Gone are the days of 45-minute sessions on the treadmill—you just have to exercise harder for 20 minutes, and you’re set. It seems like a great deal. And that’s why headlines like “This workout reverses signs of aging, according to science” and “Study identifies best exercise to reverse signs of aging” are so clickable. It’s one thing to know that a brief period of high activity might help you shed pounds, but it’s tantalizing to think that crunching your work-out into one short, sweaty burst might actually be the secret to staying forever young.
Both of those headlines refer to the same study, which came out in the journal Cell Metabolism at the beginning of March. So here’s the good news: they’re not technically wrong. HIIT does reverse signs of aging at the cellular level, which isn’t an entirely new finding though it’s still exciting to have more detailed data on how this kind of exercise benefits the body. Unfortunately, as with all exercise studies, its findings are fraught with caveats.
Let’s start with the basics. This study compared HIIT to two other kinds of exercise: resistance training (weight training) and a combination of HIIT and resistance. The HIIT group trained five days a week (with three of those devoted to high intensity biking) while the resistance group trained four days a week. The combination group did, duh, a combination, though it’s worth noting they did so at a lower intensity than either of the other groups.